It is possible for a home gardener to learn how to graft citrus. The most commonly used method of grafting citrus is called the inverted T-bud. A step by step guide can be found here: http://edis.ifas.ufl.edu/hs116

Unfortunately, although the procedures involved in T-budding are relatively easy to understand, translating them to success is often not and most people are not successful in their first attempt at grafting.